This invention relates to a method for making metallic cores and the like made from metallic oxides. Such cores made in accordance with this invention are most advantageously employable as electric, electronic, or magnetic elements for various appliances.
Cores made from oxides of specific alloys are widely used today as electric, electronic, or magnetic elements of electric appliances. A typical example of such cores is the well known ferrite core. Molds of this kind have been made generally by roasting a metallic alloy, prefiring it and molding its powders to a compact element, and then firing it again. As these manufacturing steps, especially roasting, prefiring and firing steps are largely influenced by oxygen, it is essential for producing cores of uniform electrical characteristics to take great care to control the amount of oxygen which is present during the steps. However, in practice, the control of the amount of oxygen is extremely difficult though not impossible. And, in fact, cores thus produced by conventional methods are checked of their characteristics for all of them. As their characteristics vary to each other and by each lot, a sampling inspection can hardly be adopted there.